The present invention relates to a rotary cylindrical tobacco drying machine and in particular to an improvement in the technology for preventing the excessive drying of the front and rear ends of the tobacco raw material flow in a drying machine.
Prior art rotary cylindrical tobacco drying machine is known in which a heat source for drying is automatically controlled in response to signals from moisture and weight provided at pretreatment and post-treatment process lines for providing uniformly dried tobacco leaves. Japanese Patent Publication No. 50-6556 discloses an apparatus in which a drying heat source is constantly maintained and the amount of water sprayed into an exit of the drying machine is controlled in response to a signal from a moisture meter at a post-treatment process line of the drying machine.
However these drying machines mainly aim at control at steady state and cannot sufficiently prevent excessive drying at unsteady state such as front and rear ends of the material flow.